1. Field of the Invention
The invention relates to a combination switch device having lever switches releasably attached thereto.
2. Description of the Related Art
In order to reduce the weight of a motor vehicle, recently there has been a tendency toward applying electronic systems (multiplex communications and the like) to electrical instruments attached to the motor vehicle. As part of such development, the application of an electronic system to a combination switch device for controlling lamps, wipers, and the like, that is attached to the periphery of the steering wheel column, has been under study. As a conventional combination switch device of this type, one that is shown in FIG. 7 has been proposed.
FIG. 7 is a top view in section of such conventional combination switch device. This combination switch device 1 includes: a turn lever switch 3 for operating head lamps, turn signal lamps, and the like; a wiper lever switch 5 for operating wipers, washers, and the like; a body 7 that allows the steering shaft to be inserted thereinto; and a control unit 9 having a control circuit formed therein.
The turn lever switch 3 and the wiper lever switch 5 are substantially conical, and respectively include: operation levers 3a, 5a that can be turned when an operator moves the distal ends thereof; and lever switch portions 3b, 5b that switch connections based on the turning of the operation levers 3a, 5a. Further, these lever switches 3 and 5 respectively have knob switch portions 3c, 5c of a pushbutton type arranged inside the operation levers 3a, 5a. The turn lever switch 3 and the wiper lever switch 5 are separated (into units) for maintenance considerations, and are inserted so as to slide into switch assembly containing portions 11 and 13 of the body 7 from both right and left sides of the body 7, respectively, to be fixed to the body 7.
On the other hand, the control unit 9 is disposed in a control unit containing portion 1S within the body 7, the control unit containing portion 15 being closer to the engine side (the lower side as viewed in FIG. 7) than the turn lever switch 3 and the wiper lever switch 5.
With respect to electrical connection of the turn lever switch 3 and the wiper lever switch 5 to the control unit 9, bus bars 25 for transmitting signals and currents are incorporated in the body 7, and the control unit 9 is connected to the bus bars 25. Further, at the time of attaching the lever switches 3 and 5 to the body 7, assembling-side connection terminals 21 and 23 arranged on the lever switches 3 and 5 are connected to receiving-side connection terminals 17 and 19 arranged on the switch assembly containing portions 11 and 13 of the body 7 simultaneously, so that the lever switches 3 and 5 are electrically connected to the bus bars 25. Therefore, in this combination switch device 1, mechanical assembly of the lever switches 3 and 5 to the body 7 and electrical connection of the lever switches 3 and 5 to the control unit 9 can be implemented simultaneously. As a result, this conventional combination switch device has been successful not only in improving assembling performance but also in downsizing wiring boards and curtailing the number of parts compared with other conventional combination switch devices prior to this device.
As shown in FIG. 7, in the case where the knob switch portions 3c and 5c and the lever switch mechanisms (lever switch portions 3b and 5b) have been electrically connected in advance to the assembling-side connection terminals 21 and 23 in particular, the lever switches 3 and 5 can be electrically connected completely whenever the lever switches 3 and 5 are attached to the body 7. As a result, assembling performance can be further improved.
However, in the aforementioned conventional combination switch device 1, the lever switches 3 and 5 are separated from the control unit 9 that is in the body 7. Therefore, the number of bus bars within the body for connecting the lever switches 3 and 5 to the control unit 9 is increased, and this has elevated the cost of manufacture. That is, as shown in FIG. 8, the bus bars 25 require bus bars 25a and bus bars 25b. The bus bars 25a are arranged so as to connect between the switch assembly containing portions 11 and 13 respectively formed on both right and left sides of the body 7. The bus bars 25b are arranged within the switch assembly containing portion 13 on one side.
These bus bars 25a and 25b will be described in more detail. If, as shown, e.g., in FIG. 7, the control unit 9 is arranged in the control unit containing portion 15 formed on the side (on the left side as viewed in FIG. 7) to which the wiper lever switch 5 is connected, and if the turn lever switch 3 and the wiper lever switch 5 respectively have the functions such as shown in FIG. 9, then the bus bars 25a connect leads wired to a contact board 3a of the turn lever switch 3 to the control unit 9 via the assembling-side connection terminals 21 and the receiving-side connection terminals 17 as shown in FIG. 9. On the other hand, the bus bars 25b connect leads wired to a contact board 5a of the wiper lever switch 5 to the control unit 9 via the assembling-side connection terminals 23 and the receiving-side connection terminals 19.
Further, in the construction of the aforementioned combination switch device 1, the body is so shaped as to correspond to the number of bus bars and therefore, any increase in the number of bus bars has increased the size of the body, which is another problem.